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Abstract:

A transformer may include a first and a second continuous single piece
multi-turn helical winding, one concentrically received by the other. The
turns of the windings are electrically insulated from one another and
spaced sufficiently close together to permit inductive coupling
therebetween. The turns may be formed of a conductor having a rectangular
cross-section, which may, or may not, include an electrically insulative
sheath. The single piece multi-turn helical windings may have a
continuous or smooth radius of curvature, with no discontinuities or
singularities between first and second end terminals. The transformer may
be formed by wrapping electrical conductor about a winding form. The
transformer may be used in various electrical circuits, for example
converter circuits.

Claims:

1. A transformer, comprising: a first continuous single piece multi-turn
helical winding having at least a first terminal and a second terminal;
and a second continuous single piece multi-turn helical winding having at
least a first terminal and a second terminal, a portion of the second
continuous single piece multi-turn helical winding between the first and
the second terminals received concentrically within an inner diameter of
the first continuous single piece multi-turn helical winding, the portion
of the second continuous single piece multi-turn helical winding spaced
sufficiently closely to the first continuous single piece multi-turn
helical winding to permit inductive coupling therebetween in response to
a current running through at least one of the first or the second
continuous single piece multi-turn helical windings, wherein at least one
of the first or the second continuous single piece multi-turn helical
winding consists only of an electrical conductor and an electrically
insulative sheath that consists only of an electrically insulative
material that in use electrically insulates the electrical conductor
between the first and the second terminals thereof from the other one of
the first or the second continuous single piece multi-turn helical
windings, wherein the electrical conductor of the at least one of the
first or the second continuous single piece multi-turn helical windings
has a rectangular cross-section taken perpendicular to a longitudinal
axis of the first or the second continuous single piece multi-turn
helical windings at a point along the longitudinal axis.

2. The transformer of claim 1 wherein the electrically insulative
material consists of only a single electrically insulative material.

3. The transformer of claim 1 wherein both of the first and the second
continuous single piece multi-turn helical windings consist only of an
electrical conductor and an electrically insulative sheath consisting of
only an electrically insulative material that in use electrically
insulates the electrical conductor between the first and the second
terminals thereof; and wherein the electrically insulative material on at
least one of the first continuous single piece multi-turn helical winding
or the second continuous single piece multi-turn helical winding consists
of only a single electrically insulative material.

4. The transformer of claim 1 wherein the first and the second continuous
single piece multi-turn helical windings each have a smooth radius of
curvature with no discontinuities between the first terminal and the
second terminal as projected on an X-Y plane that is perpendicular to a
respective longitudinal axis of the first and the second continuous
single piece multi-turn helical windings.

5. The transformer of claim 1 wherein at least one of the first or the
second continuous single piece multi-turn helical windings is cylindrical
having a circular cross-section taken along a longitudinal axis of the
first or the second continuous single piece multi-turn helical winding.

6. The transformer of claim 1 wherein the first continuous single piece
multi-turn helical winding has only two terminals, each of the first and
the second terminals thereof extending from a respective end of the first
continuous single piece multi-turn helical winding and wherein the second
continuous single piece multi-turn helical winding has only two
terminals, each of the first and the second terminals thereof extending
from a respective end of the second continuous single piece multi-turn
helical winding.

7. The transformer of claim 1, further comprising: at least a portion of
a core received within an inner diameter of at least one of the first or
the second continuous single piece multi-turn helical windings.

8. The transformer of claim 1, further comprising: at least a portion of
a ferrous core received within an inner diameter of at least one of the
first or the second continuous single piece multi-turn helical windings.

9. The transformer of claim 1 wherein the first continuous single piece
multi-turn helical winding has more turns than the second continuous
single piece multi-turn helical winding.

10. The transformer of claim 1 wherein the first continuous single piece
multi-turn helical winding has less turns than the second continuous
single piece multi-turn helical winding.

11. A power converter, comprising: a first continuous single piece
multi-turn helical winding having at least a first terminal and a second
terminal; a second continuous single piece multi-turn helical winding
having at least a first terminal and a second terminal, a portion of the
second continuous single piece multi-turn helical winding between the
first and the second terminals received concentrically within an inner
diameter of the first continuous single piece multi-turn helical winding,
the portion of the second continuous single piece multi-turn helical
winding spaced sufficiently closely to the first continuous single piece
multi-turn helical winding to permit inductive coupling therebetween in
response to a current running through at least one of the first or the
second continuous single piece multi-turn helical windings, wherein at
least one of the first or the second continuous single piece multi-turn
helical winding consists only of an electrical conductor and an
electrically insulative sheath consisting only of an electrically
insulative material that in use electrically insulates the electrical
conductor between first and the second terminals thereof from the other
one of the first or the second continuous single piece multi-turn helical
windings, the electrical conductor of the at least one of the first or
the second continuous single piece multi-turn helical windings has a
rectangular cross-section taken perpendicular to a longitudinal axis of
the first or the second continuous single piece multi-turn helical
windings at a point along the longitudinal axis; and at least one switch
operable to interrupt a flow of current through one of the first or the
second continuous single piece multi-turn helical windings.

12. The power converter of claim 11 wherein the electrically insulative
material consists of only a single electrically insulative material.

13. The transformer of claim 11 wherein both of the first and the second
continuous single piece multi-turn helical windings consist only of an
electrical conductor and an electrically insulative sheath consisting
only of an electrically insulative material that in use electrically
insulates the electrical conductor between the first and the second
terminals thereof; and wherein the electrically insulative material on at
least one of the first continuous single piece multi-turn helical winding
or the second continuous single piece multi-turn helical winding consists
of a single electrically insulative material.

14. A method of forming a transformer, the method comprising: forming a
first continuous single piece multi-turn helical winding consisting only
of a first electrical conductor and an electrically insulative sheath
consisting only of an electrically insulative material in which the first
electrical conductor is received, the first electrical conductor having a
rectangular cross-section taken perpendicular to a longitudinal axis of
the first continuous single piece multi-turn helical winding at a point
along the longitudinal axis; and forming a second continuous single piece
multi-turn helical winding comprising a second electrical conductor
having a rectangular cross-section taken perpendicular to a longitudinal
axis of the second continuous single piece multi-turn helical winding at
a point along the longitudinal axis; and concentrically locating one of
the first or the second continuous single piece multi-turn helical
winding in an inner diameter of the other one of the first or the second
continuous single piece multi-turn helical winding, at least portions of
the first and the second continuous single piece multi-turn helical
winding spaced sufficiently closely to one another to cause inductive
coupling therebetween in response to a current passing through at least
one of the first or the second continuous single piece multi-turn helical
windings.

15. The method of claim 14 wherein concentrically locating one of the
first or the second continuous single piece multi-turn helical winding in
an inner diameter of the other one of the first or the second continuous
single piece multi-turn helical winding includes concentrically locating
the first continuous single piece multi-turn helical winding in the inner
diameter of the second continuous single piece multi-turn helical
winding.

16. The method of claim 14 wherein concentrically locating one of the
first or the second continuous single piece multi-turn helical winding in
an inner diameter of the other one of the first or the second continuous
single piece multi-turn helical winding includes concentrically locating
the second continuous single piece multi-turn helical winding in the
inner diameter of the first continuous single piece multi-turn helical
winding.

17. The method of claim 14 wherein forming a second continuous single
piece multi-turn helical winding comprising a second electrical conductor
includes forming the second continuous single piece multi-turn helical
winding consisting only of the second electrical conductor and an
electrically insulative sheath consisting only of an electrically
insulative material in which the second electrical conductor is received.

18. The method of claim 14 wherein forming a first continuous single
piece multi-turn helical winding consisting of a first electrical
conductor and an electrically insulative sheath in which the first
electrical conductor is received includes wrapping the electrically
insulative sheath and the first electrical conductor about a winding form
to form the first continuous single piece multi-turn helical winding with
a smooth radius of curvature having no discontinuities between a first
terminal and a second terminal thereof.

19. The method of claim 14 wherein forming a second continuous single
piece multi-turn helical winding comprising a second electrical conductor
includes wrapping the second electrical conductor about a winding form to
form the second continuous single piece multi-turn helical winding with a
smooth radius of curvature having no discontinuities between a first
terminal and a second terminal thereof.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser.
No. 12/581,551 filed on Oct. 16, 2009 which is incorporated herein by
reference in its entirety.

BACKGROUND

[0002] 1. Field

[0003] This disclosure generally relates to transformers having primary
and secondary windings.

[0004] 2. Description of the Related Art

[0005] Transformers are useful for stepping up or stepping down a voltage
and/or for electrically isolating two portions of a circuit.

[0006] A transformer typically includes at least two windings of
electrically conductive material such as wire. The windings are
electrically isolated from one another but spaced sufficient close
together such that an electrical current flow through one winding will
induce an electrical current to flow in the other winding. The winding
through which the current is driven is typically denominated as the
primary winding, while the winding in which the current is induced is
typically denominated as the secondary winding. The transformer may also
include a core, for example a magnetic or ferrous core extending between
the windings.

[0007] A large variety of transformers of various designs are currently
commercially available. Numerous transformers of other designs have been
available in the past. Numerous other transformer designs have been
proposed.

[0008] In many applications, transformer size and/or weight are important
factors in realizing a practical and/or commercially successful device.
For example, transformers for use in avionics typically must be
lightweight and may need to occupy a small volume. Such applications,
however, typically require high performance. Performance may be dictated
by a number of factors; for example, the amount of conductive material in
the windings, the surface area of the windings, and/or the proximity of
the windings to one another. Many applications may additionally, or
alternatively, require low-cost transformers. Cost may be dictated by a
number of factors including type of materials, amount of materials,
and/or complexity of manufacture, among other factors.

[0009] New transformer designs and methods of manufacture of transformers
are desirable to address at least some of the disparate needs of various
technical applications that employ transformers.

BRIEF SUMMARY

[0010] A transformer may be summarized as including a first continuous
single piece multi-turn helical winding having at least a first terminal
and a second terminal; and a second continuous single piece multi-turn
helical winding having at least a first terminal and a second terminal, a
portion of the second continuous single piece multi-turn helical winding
between the first and the second terminals received concentrically within
an inner diameter of the first continuous single piece multi-turn helical
winding, the portion of the second continuous single piece multi-turn
helical winding spaced sufficiently closely to the first continuous
single piece multi-turn helical winding to permit inductive coupling
therebetween in response to a current running through at least one of the
first or the second continuous single piece multi-turn helical windings,
wherein at least one of the first or the second continuous single piece
multi-turn helical winding consists of an electrical conductor and an
electrically insulative sheath that electrically insulates the electrical
conductor between first and the second terminals thereof from the other
one of the first or the second continuous single piece multi-turn helical
windings.

[0011] The electrical conductor of the at least one of the first or the
second continuous single piece multi-turn helical windings may have a
rectangular cross-section taken perpendicular to a longitudinal axis of
the first or the second continuous single piece multi-turn helical
windings at a point along the longitudinal axis. Both of the first and
the second continuous single piece multi-turn helical windings may
consist of an electrical conductor and an electrically insulative sheath
that electrically insulates the electrical conductor between the first
and the second terminals thereof. The first and the second continuous
single piece multi-turn helical windings may each have a smooth radius of
curvature with no discontinuities between the first terminal and the
second terminal as projected on an X-Y plane that is perpendicular to a
respective longitudinal axis of the first and the second continuous
single piece multi-turn helical windings. At least one of the first or
the second continuous single piece multi-turn helical windings may be
cylindrical having a circular cross-section taken along a longitudinal
axis of the first or the second continuous single piece multi-turn
helical winding. The first continuous single piece multi-turn helical
winding may have only two terminals, each of the first and the second
terminals thereof extending from a respective end of the first continuous
single piece multi-turn helical winding and wherein the second continuous
single piece multi-turn helical winding may have only two terminals, each
of the first and the second terminals thereof extending from a respective
end of the second continuous single piece multi-turn helical winding. The
transformer may further include at least a portion of a core received
within an inner diameter of at least one of the first or the second
continuous single piece multi-turn helical windings. The transformer may
further include at least a portion of a ferrous core received within an
inner diameter of at least one of the first or the second continuous
single piece multi-turn helical windings. The first continuous single
piece multi-turn helical winding may have more turns than the second
continuous single piece multi-turn helical winding. The first continuous
single piece multi-turn helical winding may have less turns than the
second continuous single piece multi-turn helical winding.

[0012] A method of forming a transformer may be summarized as including
forming a first continuous single piece multi-turn helical winding
consisting of a first electrical conductor and an electrically insulative
sheath in which the first electrical conductor is received; and forming a
second continuous single piece multi-turn helical winding comprising a
second electrical conductor; and concentrically locating one of the first
or the second continuous single piece multi-turn helical winding in an
inner diameter of the other one of the first or the second continuous
single piece multi-turn helical winding, at least portions of the first
and the second continuous single piece multi-turn helical winding spaced
sufficiently closely to one another to cause inductive coupling
therebetween in response to a current passing through at least one of the
first or the second continuous single piece multi-turn helical windings.

[0013] Concentrically locating one of the first or the second continuous
single piece multi-turn helical winding in an inner diameter of the other
one of the first or the second continuous single piece multi-turn helical
winding may include concentrically locating the first continuous single
piece multi-turn helical winding in the inner diameter of the second
continuous single piece multi-turn helical winding. Concentrically
locating one of the first or the second continuous single piece
multi-turn helical winding in an inner diameter of the other one of the
first or the second continuous single piece multi-turn helical winding
may include concentrically locating the second continuous single piece
multi-turn helical winding in the inner diameter of the first continuous
single piece multi-turn helical winding. Forming a second continuous
single piece multi-turn helical winding may include a second electrical
conductor includes forming the second continuous single piece multi-turn
helical winding consisting of the second electrical conductor and an
electrically insulative sheath in which the second electrical conductor
is received. Forming a first continuous single piece multi-turn helical
winding consisting of a first electrical conductor and an electrically
insulative sheath in which the first electrical conductor is received may
include wrapping the electrically insulative sheath and the first
electrical conductor about a winding form to form the first continuous
single piece multi-turn helical winding with a smooth radius of curvature
having no discontinuities between a first terminal and a second terminal
thereof. Forming a second continuous single piece multi-turn helical
winding comprising a second electrical conductor may include wrapping the
second electrical conductor about a winding form to form the second
continuous single piece multi-turn helical winding with a smooth radius
of curvature having no discontinuities between a first terminal and a
second terminal thereof.

[0014] A power converter may be summarized as including a first continuous
single piece multi-turn helical winding having at least a first terminal
and a second terminal; a second continuous single piece multi-turn
helical winding having at least a first terminal and a second terminal, a
portion of the second continuous single piece multi-turn helical winding
between the first and the second terminals received concentrically within
an inner diameter of the first continuous single piece multi-turn helical
winding, the portion of the second continuous single piece multi-turn
helical winding spaced sufficiently closely to the first continuous
single piece multi-turn helical winding to permit inductive coupling
therebetween in response to a current running through at least one of the
first or the second continuous single piece multi-turn helical windings,
wherein at least one of the first or the second continuous single piece
multi-turn helical winding consists of an electrical conductor and an
electrically insulative sheath that electrically insulates the electrical
conductor between first and the second terminals thereof from the other
one of the first or the second continuous single piece multi-turn helical
windings; and at least one switch operable to interrupt a flow of current
through one of the first or the second continuous single piece multi-turn
helical windings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0015] In the drawings, identical reference numbers identify similar
elements or acts. The sizes and relative positions of elements in the
drawings are not necessarily drawn to scale. For example, the shapes of
various elements and angles are not drawn to scale, and some of these
elements are arbitrarily enlarged and positioned to improve drawing
legibility. Further, the particular shapes of the elements as drawn, are
not intended to convey any information regarding the actual shape of the
particular elements, and have been solely selected for ease of
recognition in the drawings.

[0016] FIG. 1 is a front top isometric view of a transformer having first
and second continuous single piece multi-turn helical windings, one
received concentrically within the other, according to one illustrated
embodiment.

[0017] FIG. 2 is a top plan view of the transformer of FIG. 1.

[0018] FIG. 3 is a front elevational view of the transformer of FIG. 1.

[0019] FIG. 4 is a front top isometric view of a transformer in which a
core is received by the first and second continuous single piece
multi-turn helical windings, according to another illustrated embodiment.

[0020] FIG. 5 is an isometric view showing a continuous single piece
multi-turn helical winding being wrapped around a winding form or mandrel
to form a number of turns, according to one illustrated embodiment.

[0021] FIG. 6 is an electrical schematic diagram of a flyback converter
circuit employing a transformer having concentric first and second
continuous single piece multi-turn helical windings, according to one
illustrated embodiment.

[0022] FIG. 7 is an electrical schematic diagram of a forward converter
circuit employing a transformer having concentric first and second
continuous single piece multi-turn helical windings, according to one
illustrated embodiment.

[0023] FIG. 8 is an electrical schematic diagram of a two transistor
forward converter circuit employing a transformer having concentric first
and second continuous single piece multi-turn helical windings, according
to one illustrated embodiment.

[0024] FIG. 9 is an electrical schematic diagram of an H-bridge converter
circuit employing a transformer having concentric first and second
continuous single piece multi-turn helical windings, according to one
illustrated embodiment.

DETAILED DESCRIPTION

[0025] In the following description, certain specific details are set
forth in order to provide a thorough understanding of various disclosed
embodiments. However, one skilled in the relevant art will recognize that
embodiments may be practiced without one or more of these specific
details, or with other methods, components, materials, etc. In other
instances, well-known structures associated with transformers, circuits
employing transformers, and machinery useful in manufacturing
transformers have not been shown or described in detail to avoid
unnecessarily obscuring descriptions of the embodiments.

[0026] Unless the context requires otherwise, throughout the specification
and claims which follow, the word "comprise" and variations thereof, such
as, "comprises" and "comprising" are to be construed in an open,
inclusive sense, that is as "including, but not limited to."

[0027] Reference throughout this specification to "one embodiment" or "an
embodiment" means that a particular feature, structure or characteristic
described in connection with the embodiment is included in at least one
embodiment. Thus, the appearances of the phrases "in one embodiment" or
"in an embodiment" in various places throughout this specification are
not necessarily all referring to the same embodiment. Further more, the
particular features, structures, or characteristics may be combined in
any suitable manner in one or more embodiments.

[0028] As used in this specification and the appended claims, the singular
forms "a," "an," and "the" include plural referents unless the content
clearly dictates otherwise. It should also be noted that the term "or" is
generally employed in its sense including "and/or" unless the content
clearly dictates otherwise.

[0029] The headings and Abstract of the Disclosure provided herein are for
convenience only and do not interpret the scope or meaning of the
embodiments.

[0030] FIGS. 1-3 show a transformer 10 according to one illustrated
embodiment.

[0031] The transformer 10 includes a first continuous single piece
multi-turn electrical winding 12 and a second continuous single piece
multi-turn helical winding 14. The second continuous single piece
multi-turn helical winding 14 is electrically insulated from the first
continuous single piece multi-turn helical winding 12. The turns of the
second continuous single piece multi-turn helical winding 14 are
concentrically received within the turns of the first continuous single
piece multi-turn helical winding 12, co-axially aligned along a
longitudinal axis 16. The turns of the first and second continuous single
piece multi-turn helical windings 12, 14 are spaced closely enough
together to provide inductive coupling therebetween. Hence, an outer
diameter OD2 (FIG. 2) of the second continuous single piece
multi-turn helical winding 14 is closely received by an inner diameter
ID1 (FIG. 2) of the first continuous single piece multi-turn helical
winding 12.

[0032] At least one of the first and/or the second continuous single piece
multi-turn helical windings 12, 14 may be formed of a conductor such as a
wire 13

[0033] (FIG. 5). The wire 13 may advantageously have a rectangular cross
section. The rectangular cross section may advantageously be relatively
thick (i.e., thicker than either a heavy gauge foil or printed trace of
conductive material). At least one of the first and/or the second
continuous single piece multi-turn helical windings 12, 14 may have an
electrically insulative sheath 15 (FIG. 5) that at least partially
surrounds the electrical conductor over at least some portion of a length
of the first and/or second continuous single piece multi-turn helical
windings 12, 14. In some embodiments, only one of the first or the second
continuous single piece multi-turn helical windings 12, 14 carries the
electrically insulative sheath, providing electrical insulation between
that electrical conductor and the electrical conductor forming the other
one of the continuous single piece multi-turn helical windings 12, 14.
The electrically insulative sheet can be formed of any of a large variety
of electrically insulative materials, for example various electrically
insulative polymers (e.g., PTFE or TEFLON®, PVC, KAPTON®, rubber,
polyethylene, or polypropylene).

[0034] As illustrated in FIGS. 1-3, the first and the second continuous
single piece multi-turn helical windings 12, 14 may be cylindrical,
having a circular cross section. Other embodiments may employ other
geometrical shapes, for example conic sections such as a cone,
frusto-conical or hyperbola.

[0035] Being wound instead of folded, the first and/or second continuous
single piece multi-turn helical windings 12, 14 may have a continuous or
smooth radius of curvature when an outer diameter OD1, OD2 is
projected on an X-Y plane (not shown) that is perpendicular to a
longitudinal axis 16 (FIGS. 1, 3). In particular, the radius of curvature
of the first and second continuous single piece multi-turn helical
windings 12, 14 may have no discontinuities or singularities between a
first terminal 12a, 14a, respectively, and a second terminal 12b, 14b,
respectively.

[0036] The first and second continuous single piece multi-turn helical
windings 12, 14 may have only two terminals, one at each, 12a, 12b, 14a,
14b. The terminals 12a, 12b, 14a, 14b extend from respective ends of the
first and second continuous single piece multi-turn helical windings 12,
14. The terminals 12a, 12b, 14a, 14b allow electrical connections to be
made to respective circuits or portions of a circuit. Thus the
transformer 10 may be easily integrated into various circuits.

[0037] A ratio of turns of the first continuous single piece multi-turn
helical winding 12 to turns of the second continuous single piece
multi-turn helical winding 14 may, for example, be equal to or close to
1:1. The ratio of turns of the first continuous single piece multi-turn
helical winding 12 to turns of the second continuous single piece
multi-turn helical winding 14 may be greater than 1:1, for example 2:1,
3:1, 4:1 or more. The ratio of turns of the first continuous single piece
multi-turn helical winding 12 to turns of the second continuous single
piece multi-turn helical winding 14 may less than 1:1, for example 1:2,
1:3, 1:4 or less. Transformers may employ any other ratios of turns than
those ratios generally described above.

[0038] FIG. 4 shows a transformer 20 according to another illustrated
embodiment.

[0039] The transformer 20 includes a first continuous single piece
multi-turn helical winding 22, and a second continuous single piece
multi-turn helical winding 24 concentrically received within an inner
diameter ID1 of the first continuous single piece multi-turn helical
winding 22. The first and the second continuous single piece multi-turn
helical windings 22, 24 each have respective terminals 22a, 22b, 24a, 24b
located at the ends thereof.

[0040] The transformer 20 also includes a core 26 received through a
passage formed by the inner diameters ID2 of the second continuous
single piece multi-turn helical windings 24. The core 26 may, for
example, take the form of a magnetizable or ferrite material, for
instance a rod or bar of ferrite, samarium cobalt or
neodymium-iron-boron.

[0041] While not illustrated, the transformer 20 may include a housing.
The housing may include one or more parts, for example a first portion
and a second portion. The first portion may include an end cover and a
core, for example magnetizable or ferrite core. The core may be formed as
a separate individual piece from the first and second parts.
Alternatively, the core may be formed integrally as a single piece with
either the first portion or second portion. Alternatively, a respective
portion of the core may be formed integrally with the first portion 60a
or second portion 60b. The first portion and second portions may
selectively securely attach to one another. Employing two or more
portions advantageously allows a multi-piece housing to be installed
after the first and second continuous single piece multi-turn helical
windings are concentrically mounted, one within the other.

[0042] FIG. 5 shows a method of forming a transformer according to one
illustrated embodiment.

[0043] A supply reel 30 supplies an electrical conductor 32 to a winding
form or mandrel 34. The supply reel 30 may rotate about a longitudinal
axis 33 of the supply reel. The electrical conductor 32 is wrapped about
the winding form or mandrel 34 to form a continuous single piece
multi-turn helical winding. While the winding form or mandrel 34 is
illustrated as having a cylindrical shape with a circular cross-section,
other shapes may be employed to achieve continuous single piece
multi-turn helical windings of other configurations.

[0044] The electrical conductor 32 may pass through one or more rollers or
pairs of rollers 36 while advancing toward the winding form or mandrel
34. Such may be used to shape the electrical conductor 32, for example to
facilitate the formation of the smooth radius of curvature for the turns
of the continuous single piece multi-turn helical winding. Additionally
or alternatively, electrical conductor 32 may pass through one or more
cutters 38 to separate the continuous single piece multi-turn helical
winding from the supply reel 30.

[0045] In some embodiments, the winding form or mandrel 34 may be kept
fixed while the electrical conductor 32 and/or supply reel 30 is rotated
thereabout. In other embodiments, the winding form or mandrel 34 may
rotate about a longitudinal axis 40 while the supply reel 30 rotates
about respective axis 33 to supply the electrical conductor 32 to the
winding form or mandrel 34. In other embodiments, the supply reel 30 may
additionally, or alternatively, rotate about the longitudinal axis 40 of
the winding form or mandrel 34.

[0047] The flyback converter 60 may electrically couple a power source V
to a load L via the transformer T1. A switch S1 alternating
electrically couples and decouples the power source V to a primary
winding of the transformer T1 to produce a changing current
therethrough. The changing current passing through the primary winding of
the transformer T1 induces a current in a secondary winding of the
transformer T1.

[0048] The secondary winding is electrically coupled to the load L via a
diode D1. A smoothing capacitor C1 may be electrically coupled
in parallel across the load L.

[0049] FIG. 7 shows a single transistor forward converter 70 that employs
a transformer T1 having concentrically arranged continuous single
piece multi-turn helical windings, according to another illustrated
embodiment.

[0050] The single transistor forward converter 70 may electrically couple
a power source V to a load L via the transformer T1. A switch
S1 alternating electrically couples and decouples the power source V
to a primary winding of the transformer T1 to produce a changing
current therethrough. The changing current passing through the primary
winding of the transformer T1 induces a current in a secondary
winding of the transformer T1.

[0051] The secondary winding is electrically coupled to the load L via a
diode D1, inductor L1, and via a diode D2 electrically
coupled in parallel across the load L. A smoothing capacitor C1 may
also be electrically coupled in parallel across the load L.

[0052] FIG. 8 shows a two transistor forward converter 80 that employs a
transformer T1 having concentrically arranged continuous single
piece multi-turn helical windings, according to another illustrated
embodiment.

[0053] The two transistor forward converter 80 may electrically couple a
power source V to a load L via the transformer T1. A pair of
switches S1, S2 (e.g., transistors such as FETs or IGBTs)
concurrently electrically couple (i.e., closed or on) and decouple (i.e.,
open or off) the power source V to a primary winding of the transformer
T1. A pair of diodes D1, D2 are forward biased after the
switches S1, S2, open, applying a negative voltage across the
primary winding. The resulting changing current passing through the
primary winding of the transformer T1 induces a current in a
secondary winding of the transformer T1.

[0054] The secondary winding is electrically coupled to the load L via a
diode D3, inductor L1, and via a diode D4 electrically
coupled in parallel across the load L. A smoothing capacitor C1 may
also be electrically coupled in parallel across the load L.

[0056] The H-bridge converter 90 may electrically couple a power source V
to a load L via the transformer T1. and an inductor L1. A input
capacitor C1 may be electrically coupled in parallel across the
power source. Two pairs of switches S1, S2 and S3, S4
alternating electrically couple and decouple the power source V to a
primary winding of the transformer T1 to produce a changing,
alternating current therethrough. Thus, each switch S1, S2 of
the first pair open and close together, and each switch S3, S4
open and close together, with the second pair of switches S3,
S4, operating opposite the first pair of switches S1, S2.
The changing current passing through the primary winding of the
transformer T1 induces a current in a secondary winding of the
transformer T1.

[0057] The secondary winding of the transformer T1 is electrically coupled
to the load L via a set of diode D3-D4 arranged in a bridge to
rectify the induced current. A smoothing capacitor C2 may be
electrically coupled in parallel across the load L.

[0058] The above description of illustrated embodiments, including what is
described in the Abstract, is not intended to be exhaustive or to limit
the embodiments to the precise forms disclosed. Although specific
embodiments of and examples are described herein for illustrative
purposes, various equivalent modifications can be made without departing
from the spirit and scope of the disclosure, as will be recognized by
those skilled in the relevant art. The teachings provided herein of the
various embodiments can be applied to other transformers, not necessarily
the exemplary transformers generally described above. The teachings
provided herein of the various embodiments can be applied to other
circuits, including other converter circuits, not necessarily the
exemplary converter circuits generally described above.

[0059] The various embodiments described above can be combined to provide
further embodiments. To the extent that they are not inconsistent with
the specific teachings and definitions herein, U.S. Patent Application
Publication No. 2011/0090038, entitled "Transformer Having Interleaved
Windings and Method of Manufacture of Same" filed concurrently herewith
(Atty. Docket No. 480127.404) are incorporated herein by reference, in
its entirety. Aspects of the embodiments can be modified, if necessary,
to employ systems, circuits and concepts of the various patents,
applications and publications to provide yet further embodiments.

[0060] These and other changes can be made to the embodiments in light of
the above-detailed description. In general, in the following claims, the
terms used should not be construed to limit the claims to the specific
embodiments disclosed in the specification and the claims, but should be
construed to include all possible embodiments along with the full scope
of equivalents to which such claims are entitled. Accordingly, the claims
are not limited by the disclosure.